Answer: b
Explanation: We know that the propogation constant is a complex function and the real part of the complex propogation constant is a measure of the change in magnitude of the current or voltage in the network known as attenuation constant and imaginary part is a measure of the difference in phase between the input and output currents or voltages known as phase shift constant. ϒ = α + jβ.

Answer: a
Explanation: If α = 0, sin β/2 = x(√(Z1/4 Z2). But sine can have a maximum value of 1. Therefore the above solution is valid only for Z1/4 Z2, and having a maximum value of unity. It indicates the condition of pass band with zero attenuation and follows the condition as -1 < Z1/4 Z2 <= 0. So β=2 sin-1⁡(√(Z1/4 Z2)).